Valve assembly having improved pump-down performance

Abstract

A valve assembly including a housing having a flow path extending to an outlet and a valve seat in the flow path and around the outlet, a slide plate located in the housing and movable transversely to a longitudinal axis of the flow path between a closed position, in which the slide plate is in contact with the valve seat and blocks flow through the flow path, and an opened position, in which the slide plate allows flow through the flow path, and wherein at least one of the slide plate and the valve seat includes at least one passageway for providing a predetermined amount of conductance between the slide plate and the valve seat when the slide plate is in the closed position.

1. A valve assembly comprising:
 a housing having a flow path extending to an outlet and defining a valve seat in the flow path and around the outlet; 
 a slide plate located in the housing and movable transversely to a longitudinal axis of the flow path between a closed position, in which the slide plate is in contact with the valve seat and blocks flow through the flow path, and an opened position, in which the slide plate allows flow through the flow path, wherein the slide plate is pivotally movable into the flow path; and 
 wherein at least one of the slide plate and the valve seat includes at least one passageway for providing a predetermined amount of conductance between the slide plate and the valve seat when the slide plate is in the closed position. 
 
   
   
     2. A valve assembly according to  claim 1 , wherein the passageway for providing the predetermined amount of conductance between the slide plate and the valve seat is defined in the slide plate. 
   
   
     3. A valve assembly according to  claim 2 , wherein the slide plate has a first surface facing away from the outlet, a second surface facing towards the outlet, and a radially outwardly facing side wall extending generally parallel with the flow path, and wherein the passageway for providing the predetermined amount of conductance between the slide plate and a seal ring is defined in the second surface and the side wall of the slide plate. 
   
   
     4. A valve assembly according to  claim 3 , wherein the passageway comprises a groove formed in the second surface and extending to the side wall of the slide plate. 
   
   
     5. A valve assembly according to  claim 3 , wherein the passageway comprises multiple grooves formed in the second surface and extending to the side wall of the slide plate. 
   
   
     6. A valve assembly according to  claim 3 , wherein the passageway comprises a bore extending from the second surface to the side wall of the slide plate, and wherein an entrance of the bore is defined in the side wall while an exit of the bore is defined in the second surface. 
   
   
     7. A valve assembly according to  claim 6 , further comprising a movable door positioned over the exit of the bore. 
   
   
     8. A valve assembly according to  claim 7 , wherein the movable door is biased closed. 
   
   
     9. A valve assembly according to  claim 8 , wherein the movable door comprises a resiliently flexible spring plate normally biased closed. 
   
   
     10. A valve assembly according to  claim 1 , wherein the slide plate is pivotally movable between a first opened position out of the flow path, and a second opened position where the slide plate is pivoted into the slide channel but axially spaced from the valve seat of the outlet, and then axially movable in the flow path to the substantially closed position in contact with the valve seat of the outlet. 
   
   
     11. A valve assembly according to  claim 10 , further comprising a shaft connected to the slide plate through an arm extending laterally from the shaft, the shaft at least partially mounted within the housing to rotate about a longitudinal axis of the shaft to allow the slide plate to rotate into the flow pat to the second opened position, and also slide substantially parallel to the axis of the flow path to allow the slide plate to move axially in the flow path to the substantially closed position in contact with the valve seat of the outlet. 
   
   
     12. A valve assembly according to  claim 11 , further including a cam mechanism coupled between the shaft and the housing to provide a combination of rotational movement and sliding movement of the shaft. 
   
   
     13. A valve assembly according to  claim 12 , wherein the cam mechanism comprises:
 a cam surface defined by the housing; and 
 a cam follower fixed to the shaft and engaging the cam surface of the housing. 
 
   
   
     14. A valve assembly according to  claim 12 , wherein the cam mechanism comprises a spring for providing sliding movement of the shaft and for normally biasing the slide plate away from the valve seat of the outlet. 
   
   
     15. A valve assembly according to  claim 1 , wherein the flow path extends from an inlet to the outlet and defines a valve seat in the flow path and around the inlet, and the assembly further comprises a seal ring coaxially positioned within the flow path between the valve set of the inlet and the slide plate, wherein the seal ring is axially movable in the flow path towards the slide plate to provide a seal between the slide plate and the valve seat of the inlet. 
   
   
     16. A valve assembly according to  claim 15 , wherein at least one of the slide plate and the seal ring includes at least one passageway for increasing conductance between the slide plate and the seal ring. 
   
   
     17. A valve assembly according to  claim 16 , wherein the at least one passageway for increasing conductance between the seal ring and the slide plate is formed in the seal ring. 
   
   
     18. A valve assembly according to  claim 1 , further comprising a spring normally biasing the slide plate away from the valve seat of the outlet. 
   
   
     19. A high purity gas delivery system including a valve assembly according to  claim 1 , and further including a process chamber connected to a vacuum pump through the valve assembly. 
   
   
     20. A valve assembly according to  claim 1 , wherein the passageway for providing the predetermined amount of conductance between the slide plate and the valve seat is defined in the valve seat. 
   
   
     21. A valve assembly according to  claim 1 , wherein a passageway for providing the predetermined amount of conductance between the slide plate and the valve seat is defined in both the slide plate and the valve seat.